diff --git a/mt5_correlation/correlation.py b/mt5_correlation/correlation.py
index 2864c7c..34ff9fc 100644
--- a/mt5_correlation/correlation.py
+++ b/mt5_correlation/correlation.py
@@ -10,6 +10,7 @@ from scipy.stats.stats import pearsonr
 import pickle
 import inspect
 import sys
+import numpy as np
 
 from mt5_correlation.mt5 import MT5
 
@@ -369,6 +370,10 @@ class Correlation:
         # Clear tick data
         self.__monitor_tick_data = {}
 
+        # Clear columns from coefficient data
+        self.coefficient_data['Last Check'] = np.NaN
+        self.coefficient_data['Last Coefficient'] = np.NaN
+
     def get_ticks(self, symbol, date_from=None, date_to=None, cache_time=0, cache_only=False):
         """
         Returns the ticks for the specified symbol. Get's from cache if available and not older than cache_timeframe.
diff --git a/mt5_correlation/gui.py b/mt5_correlation/gui.py
index 01e56e7..9d6d4c5 100644
--- a/mt5_correlation/gui.py
+++ b/mt5_correlation/gui.py
@@ -163,7 +163,7 @@ class MonitorFrame(wx.Frame):
             self.__cor.load(self.__opened_filename)
 
             # Refresh data in grid
-            self.refresh_grid()
+            self.__refresh_grid()
 
             self.SetStatusText(f"File {self.__opened_filename} loaded.", 1)
 
@@ -208,13 +208,13 @@ class MonitorFrame(wx.Frame):
         self.SetStatusText("", 1)
 
         # Show calculated data
-        self.refresh_grid()
+        self.__refresh_grid()
 
     def quit(self, event):
         # Close
         self.Close()
 
-    def refresh_grid(self):
+    def __refresh_grid(self):
         """
         Refreshes grid. Notifies if rows have been added or deleted.
         :return:
@@ -346,7 +346,7 @@ class MonitorFrame(wx.Frame):
             if reload_correlations:
                 self.__log.info("Settings updated. Updating monitoring threshold and reloading grid.")
                 self.__cor.monitoring_threshold = self.__config.get("monitor.monitoring_threshold")
-                self.refresh_grid()
+                self.__refresh_grid()
 
             if reload_logger:
                 self.__log.info("Settings updated. Reloading logger.")
@@ -438,7 +438,7 @@ class MonitorFrame(wx.Frame):
         Called on timer event. Refreshes grid and updates selected graph.
         :return:
         """
-        self.refresh_grid()
+        self.__refresh_grid()
         if len(self.__selected_correlation) == 2:
             self.show_graph(symbol1=self.__selected_correlation[0], symbol2=self.__selected_correlation[1])
 
@@ -456,6 +456,9 @@ class MonitorFrame(wx.Frame):
         if len(self.__selected_correlation) == 2:
             self.show_graph(symbol1=self.__selected_correlation[0], symbol2=self.__selected_correlation[1])
 
+        # Reload the table
+        self.__refresh_grid()
+
 
 class DataTable(wx.grid.GridTableBase):
     """
diff --git a/requirements.txt b/requirements.txt
index 4402b70..5f47362 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,4 +6,5 @@ scipy==1.6.0
 logging==0.4.9.6
 pyyaml==5.4.1
 wxpython==4.1.1
-mock==4.0.3
\ No newline at end of file
+mock==4.0.3
+numpy==1.20.0
\ No newline at end of file